Helicenes with controllable chiroptical properties: Herein, we reveal a system in which the oxidation of a phosphino group on the inner rim of a helicene derivative induces a circularly polarized luminescence (CPL) response. A helicene bearing a phosphine oxide group exhibits a markedly enhanced CPL response in the excited state compared with that of such a helicene with a corresponding phosphine. More information can be found in the Research Article by K. Usui, Y. Imai, S. Karasawa, and co-workers (DOI: 10.1002/chem.202202922).

A stable cyclobutadiene dication was isolated and structurally characterized as a bis(tribromide) salt. Unlike the folded minimum structure calculated for the parent C₄H₄²⁺ system, this dication exhibits a planar geometry in the solid state. However, calculations reveal a nearly isoenergetic folded isomer, and detailed studies employing advanced NICS methods show that, counterintuitively, cyclobutadiene dications are more aromatic when puckered rather than planar. For more information on this topic and related applications of diaminoacetylenes, see the Research Article by M. Tamm and co-workers (DOI: 10.1002/chem.202202737).

A novel class of light-responsive π-conjugated compounds incorporates photochromic torsional switches (PTS). These compounds are able to tune the planarization of their π-conjugated backbone, and thus their optical and electronic properties, by using light as an external stimulus. The PTS unit is based on a bithiophene fragment linked to a photochromic azobenzene moiety. When this PTS-containing oligothiophene is not exposed to light, the azobenzene moiety assumes its extended trans conformation, which forces the oligothiophene backbone to twist out of coplanarity. Exposure to UV light results in isomerization to the cis conformation, which allows the bithiophene fragment to assume a planar, π-conjugated conformation. More information can be found in the Research Article by D. Fazzi, E. Orentas, G. Sforazzini, and co-workers (DOI: 10.1002/chem.202202698).

NIR fluorescent lanthanide upconversion nanoprobes for in vivo detection of free radicals are summarized in this review article by Zhang, Wang, Xing and co-authors et al., mainly focusing on the latest advances of lanthanide doped upconversion nanoprobes (UCNPs) for NIR fluorescent sensing of ROS/RNS radical species, as well as their potential challenges and perspectives for further development, providing valuable insights for modern biomedical applications in the future (DOI: 10.1002/chem.202201966).

Multiple heterohelicenes involving one or more heteroatoms in the helical backbone, in light of the importance of their spanning disciplines of the chemical and material sciences, have thus attracted significant interest from various research fields. This review summarizes the current progress in the chemistry of multiple heterohelicenes, especially of those with boron, nitrogen, oxygen, silicon, sulfur, or phosphorus atoms fused into their skeletons over the past decade (2012–2022). For each of multiple heterohelicenes, their synthesis, structural features, electronic and chiroptical properties, as well as examples of their applications, are collected (DOI: 10.1002/chem.202202069).

“The oxidation of a phosphino group to the corresponding phosphine oxide on the inner rim of a helicene derivative induces a CPL response.” This and more about the story behind the front cover can be found in the article at 10.1002/chem.202202922).

Accurate detection of reactive oxygen species (ROS) and reactive nitrogen species (RNS) is of great significance. A variety of upconversion nanoparticles (UCNPs)-based near-infrared (NIR) nanoprobes for ROS and RNS detection is reviewed. Our focus is to describe how they are built and how do they work. Finally, the future opportunities and challenges for UCNPs-based NIR nanoprobes are briefly discussed, and how to improve the performance of UCNPs is also prospected.

Twist it! A light-responsive molecular design to tune the π-conjugation extension of oligothiophenes has been established. The relationship between molecular structure and optoelectronic properties was comprehensively studied both experimentally and theoretically. The results highlight the functionality of the proposed molecular architecture as a promising candidate for the development of novel light-responsive optoelectronic technologies.

YfeX, naturally a peroxidase, has great potential for the development of new carbene transferases. WT YfeX catalyzes N−H insertion (including aliphatic and secondary amines) in high yield, cyclopropanation, and most excitingly, Si−H insertion of dimethylphenylsilane. QM/MM calculations reveal details of the mechanism of the unusual Si−H insertion reaction.

Peptide self-assembling: Both, solid-state form and stereochemistry significantly influence a self-assembly process of a cyclic dipeptide, Tyr-Tyr (cYY), leading to a soft matter with different morphology and rheological properties.

Binding: This study aims to add a deeper level of knowledge to the binding interactions between G4-ligands and G4 DNA to advance the design of improved G4-ligands. This is achieved by biophysical and physicochemical evaluations complemented by computational studies of both novel and well-known G4-ligands.

A radical approach. Activations of arene C−H bonds by a photochemically excited dimagnesium(I) compound are reported (see picture, Dip=2,6-diisopropylphenyl). Experimental and theoretical evidence for the intermediacy of magnesium radicals in these reactions is presented. Such transition-metal-free C−H bond activations hold considerable potential for organic synthesis.

The cyclic anionic tetramer, [S₄N₂O₁₀]²⁻, is reported in dimeric gold complexes for the first time. The anion can be interpreted as the condensation product of two sulfate anions and two amidosulfate anions. The applied solvothermal synthesis between SO₃, P₃N₃Cl₆ and metal salts is a promising route to obtain novel nitrogen-containing sulfates.

X-ray structures of diol dehydratase (DD) and ethanolamine ammonia-lyase (EAL) complexed with adenosylmethylcobalamin (AdoMeCbl) were determined to get insights into the very low activity of AdoMeCbl. The DD active site is flexible, and AdoMeCbl binding causes large conformational changes that leave DD in the inactive state (left). The EAL active site is rigid and its binding does not induce significant conformational change (right).

Two series of biradical-metal complexes have been obtained by using an imino nitroxide biradical. Remarkably one magnetic process is found for the Dy-biradical compound while the Dy−Cu-radical compound exhibits dual relaxation processes which indicates that the second coordination sphere of Dy ion plays a crucial role in magnetic relaxation behavior.

Five-membered boron difluoro complexes using a secondary amide as an anionic ligand display large Stokes shift and significant solid-state emission. Dyes exhibiting room- temperature phosphorescence (RTP) emission in both amorphous and crystalline states are documented.

An intramolecular chlorine transfer strategy for enantioselective halopalladation cyclization of 1,6-enynes has been established to build versatile and functionally diverse α-chloromethylene-γ-butyrolactones in excellent E selectivity and enantioselectivity with good functional-group compatibility. This strategy provides a novel approach to asymmetric halopalladation and an alternative for synthesizing complex natural products.

The new cationic ruthenium [RuCl(PP)(tpy)]X (X=Cl, PF₆) complexes, prepared from [RuCl₂(PPh₃)₃] a diphosphine and 2,2′:6′,2′′-terpyridine (tpy), promote the photocatalytical transfer hydrogenation (TH) of carbonyl compounds in 2-propanol under mild conditions. Unprecedented asymmetric catalytic TH of acetophenone driven by light was obtained with ruthenium tpy complexes containing the chiral Skewphos diphosphine.

A new photocatalytic [2+2] cycloaddition reaction based on our Redox-Tag strategy was developed involving carefully designed substrates which turned out to be effective for the reaction. A radical cation was formed by oxidative single electron transfer (SET) that immediately reacted with an alkene. An aryl radical cation was generated by intramolecular SET and during the subsequent reductive SET a cyclobutane was formed.

The gas-phase reactivity of phenylferrate ions toward organyl halides is studied by a combination of tandem mass spectrometry and DFT calculations. The thus obtained results offer a sharp glimpse at the elementary step of the oxidative addition and help to improve our fundamental understanding of iron-catalyzed cross-coupling reactions.

Coordination of difluoropentathiophosphate to d10 metals results in either simple bis-chelate coordination or P−S heterolysis and capping of fluorotrithiophosphate in trinuclear and octanuclear cadmium and copper clusters. These new complexes may see use as metallothionein mimicks or in capping of CdS semiconductors.